In the case of a combustion chamber arrangement of the aforesaid generic type, in which the combustion chamber wall on the outlet side leads in an overlapping manner into a hot gas housing by means of which the hot gases which are formed inside the combustion chamber are fed to a gas turbine stage, mechanical stresses between the combustion chamber wall and the hot gas housing, contingent upon thermally different coefficients of material expansion, are consequently avoided by the combustion chamber wall leading into the hot gas housing with a radial clearance and including with this housing a gap which extends over a specific axial region.
Such combustion chamber arrangements are used for example in conjunction with so-called silo burners, DE 42 23 828 A1 being representatively referred to for a more detailed explanation thereof. Such combustion chamber arrangements are also found in the case of annular combustion chambers which provide a multiplicity of individual combustion chambers which are extended in a star-shaped arrangement around the rotor arrangement of a gas turbine installation and of which each individual combustion chamber is fired by a burner or a burner arrangement. The downstream-side ends of the individual combustion chambers lead in each case into a hot gas housing which feeds the hot gases into a first expansion stage of the gas turbine installation which is provided coaxially along the rotor arrangement. Concerning this, DE 196 15 910 B4 may be representatively referred to.
From the partial longitudinal sectional view which is schematically shown in FIG. 2, the connecting region between combustion chamber wall 1 and hot gas housing 2 is illustrated in more detail. It may be assumed that the combustion chamber wall 1 and also the hot gas housing 2 which adjoins downstream to the combustion chamber wall 1 are formed largely cylindrically and rotationally symmetrically around the axis A. It may additionally be assumed that upstream to the flow direction S which is shown in FIG. 2 a burner arrangement is provided for firing the combustion chamber 3, in which hot gases develop which propagate along the flow direction S and flow over the combustion chamber wall edge 4, which is shown in FIG. 2, into the hot gas housing 2 which directs the hot gases downstream in a gas turbine stage, which is not shown in more detail, for purposeful expansion.
For avoiding stage leakages and thermally induced mechanical stresses between the combustion chamber wall 1 and the hot gas housing 2 which adjoins it downstream, the combustion chamber wall 1 by its freely terminating combustion chamber wall edge 4 leads inside the hot gas housing 2 with an axial overlap 5, wherein the combustion chamber wall 1 has a radial clearance 6 in relation to the hot gas housing 2.
For fastening of the annular seal 9, the hot gas housing 2 makes provision on its upstream end for individual collar-like fasteners 7 which are arranged in a distributed manner in the circumferential direction around the hot gas housing 2 and which on one side are connected in a fixed manner, preferably via a weld joint 8, to the hot gas housing 2. In this case, it is to be noted that the annular seal is largely characterized by a ring which makes a temperature-dependent dilatation or restriction possible. The individual collar-like fasteners 7 engage with this annular seal 9 which fully encompasses the outer side of the combustion chamber wall 1 in the circumferential direction and is joined to this with pressing force applied in such a way that the annular seal 9 experiences an axially tight seating in relation to the combustion chamber wall 1.
In FIG. 3, an axial view of the annular seal 9 which lies around the combustion chamber wall 1 is shown. For its part, this comprises a multiplicity of individual so-called sealing segments 10 which in the circumferential direction, on the end face side, are joined to each other in pairs in each case via connecting structures 11.
The collar-like fasteners 7, as can be seen schematically in FIGS. 2 and 5, radially and axially span the individual sealing segments 10 and ensure that the individual sealing segments 10 of the annular seal 9 have a degree of freedom, which is established in the various planes, in relation to burner wall 1 and hot gas housing 2.
All the sealing segments 10 inside the annular seal 9 do not terminate flush with the outer side of the combustion chamber wall 1, but on their surface which faces the combustion chamber wall have rib-like elevations which extend parallel to each other and with the combustion chamber wall 1 therefore enclose a multiplicity of flow passages 12 through which cooling air K is directed. With reference to FIG. 2, it is apparent that the cooling air K which is directed through the individual flow passages 12 reaches the annular spatial area 13 which is radially delimited by means of the axially mutually overlapping combustion chamber wall 1 and the hot gas housing 2. As a result of the inflow of cooling air K close to the wall along the inner wall of the hot gas housing 2, film cooling develops on this, by means of which the hot gas housing can be effectively cooled in comparison to the high temperature level of the hot gases.
For reasons of a simplified installation, it is advisable not to fasten the fasteners 7, which are formed like a collar, directly on the hot gas housing 2 which in most cases is formed in one piece, but on a flange wall 15 which, via a weld joint 14, is connected flush to the hot gas housing 2 in an axial direction and, however, is furthermore considered as part of said hot gas housing 2.
The operation of such a burner arrangement, however, reveals distinctive features in need of improvement which are associated with the occurrence of local overheating phenomena at the location of the hot gas housing 2 in the region downstream of the combustion chamber wall edge 4. Such overheating phenomena occur in the form of overheated, streak-like wall regions which extend locally in the flow direction and create periodically recurring local overheating spots in the circumferential direction along the inner wall of the hot gas housing 2.
More detailed investigations have shown that the local overheated inner wall regions of the hot gas housing 2 are created as a result of, or at least in association with, hot gas circulations which occur in the region of the combustion chamber wall edge 4, as a result of which portions of the hot gas reach the annular spatial area 13 via the combustion chamber wall edge 4 and are able to locally disturb the previously described film cooling along the inner wall of the hot gas housing 2. The wall overheating which develops repeatedly in the manner of streaks downstream along the inner wall of the hot gas housing 2 can lead to irreversible wall damage, the weld joint 14, along which the flange wall 15 is connected to the rest of the hot gas housing 2, particularly suffering significant damage.